Estimation of helical angles of myosin and collagen by second harmonic generation imaging microscopy

International audienceWe performed Second Harmonic Generation (SHG) imaging microscopy of endogeneous myosin-rich and collagen-rich tissues in amphibian and mammals. We determined the relative components of the macroscopic susceptibility tensor χ(2) from polarization dependence of SHG intensity. The effective orientation angle θe of the harmonophores has been determined for each protein. For myosin we found θe ≈ 62° and this value was unchanged during myofibrillogenesis. It was also independent of the animal species (xenopus, dog and human). For collagen we found θe ≈ 49° for both type I- and type III- rich tissues. From these results we localized the source of SHG along the single helix of both myosin and collagen